glcanvas on a wxpanel?

almonj · Post by **almonj** » Mon Oct 30, 2017 6:28 pm

Is it possible to add a glcanvas to a wxpanel? I have a working canvas program where the canvas is attached to a wxframe:

When I try to add a sizer with a wxpanel to the frame I end up getting a small cube in the corner.

How do I go about getting a canvas in a window where I can also add buttons and text boxes along side of it? I'm probably making some obvious mistake but I have no idea what the proper way to do this is, and I could not find any examples of this.

Frame class

Code: Select all

M_frame::M_frame(const wxString& title)
       : wxFrame(NULL, wxID_ANY, title, wxDefaultPosition, wxSize(1024, 768))
{

    canvas = NULL;

    wxGLAttributes attribs;
    attribs.PlatformDefaults().Defaults().EndList();
    bool accepted = wxGLCanvas::IsDisplaySupported(attribs);
    if (accepted)
    {
        std::cout << "normal display attribs are supported" << std::endl;
    }
    else
    {
        std::cout << "normal display attribs failed, trying other settings" << std::endl;
        attribs.Reset();
        attribs.PlatformDefaults().RGBA().DoubleBuffer().Depth(16).EndList();
        accepted = wxGLCanvas::IsDisplaySupported(attribs);
        if (!accepted)
        {
            std::cout << "display attribs cannot be set" << std::endl;
        }
    }

    if (accepted)
    {
        canvas = new M_canvas(this, attribs);
        std::cout << "canvas created \n" << std::endl;
    }
    SetMinSize(wxSize(640,480));

    //////////////////////////////////////////////////////////////////////////////////////////
    //////////sizer panel test, when I add this the canvas turns into a small cube//////////////////////
    //////////////////////////////////////////////////////////////////////////////////////////
    
    wxBoxSizer *bsizer;
    bsizer = new wxBoxSizer(wxVERTICAL);

    m_panel = new wxPanel(this, wxID_ANY, wxDefaultPosition, wxDefaultSize, wxTAB_TRAVERSAL);
    bsizer->Add(m_panel, 1, wxEXPAND | wxALL, 5);

    this->SetSizer(bsizer);
    this->Layout();
    this->Centre(wxBOTH);

    //////////////////////////////////////////////////////////////////////////////////////////
    //////////////////////////////////////////////////////////////////////////////////////////

    wxMenu    *menufile    = new wxMenu;
    wxMenuBar *menubar     = new wxMenuBar;

    menubar->Append(menufile, "&File");

    menufile->Append(wxID_EXIT, "&Exit", "Quit the program");
    menufile->AppendSeparator();

    menufile->Append(wxID_HIGHEST + 10, "&Log window", "open Log window");
    menufile->AppendSeparator();

    SetMenuBar(menubar);

    m_log = new wxLogWindow(NULL, "log window", false, false);
    wxLog::SetActiveTarget(m_log);
    wxLogMessage("Log created");

};

Canvas class

Code: Select all

#include "glew-2.1.0/include/GL/glew.h"

#include "M_canvas.h"

#include "M_frame.h"


M_canvas::M_canvas(M_frame* parent, const wxGLAttributes& attribs)
         : wxGLCanvas(parent, attribs, wxID_ANY, wxDefaultPosition, wxDefaultSize, 0, "canvas", wxNullPalette)
{

    m_parent = parent;
    wxGLContextAttrs ctxAttribs;

    ctxAttribs.PlatformDefaults().CoreProfile().OGLVersion(3,3).EndList();

    m_context = new wxGLContext(this, NULL, &ctxAttribs);

    M_canvas::gl_init();

    gl = new GL_set();

};


M_canvas::~M_canvas()
{

    if(m_context)
    {
        SetCurrent(*m_context);
    }

    if(m_context)
    {
        delete m_context;
        m_context = NULL;
    }

}

M_canvas::gl_init()
{

    std::cout << "calling gl_init() " << std::endl;

    if (!m_context)
    {
        return false;
    }

    // Context needs to be set before openGL pointers are retrieved (glew)
    SetCurrent(*m_context);

    glewExperimental = GL_TRUE;
    GLenum err = glewInit();
    if (GLEW_OK != err)
    {
        // Problem: glewInit failed, something is seriously wrong.
        printf("Error: %s\n", glewGetErrorString(err));
        return false;
    }
    printf("Status: Using GLEW %s\n", glewGetString(GLEW_VERSION));

}

void M_canvas::paint(wxPaintEvent& WXUNUSED(event))
{

    wxPaintDC dc(this);

    SetCurrent(*m_context);

    gl->render();

    SwapBuffers();

}

BEGIN_EVENT_TABLE(M_canvas, wxGLCanvas)
    EVT_PAINT(M_canvas::paint)
END_EVENT_TABLE()

Post by **doublemax** » Mon Oct 30, 2017 7:10 pm

The wxPanel should be the only child of the wxFrame.
Then you add a wxSizer to the panel and put the wxGLCanvas (and probably other controls) into the sizer.
The wxGLCanvas and these controls must have the wxPanel as parent.
As the wxGLCanvas has no natural "best size" you need to set the sizer flags (wxEXPAND) and proportion parameter so that it consumes all available space.

ONEEYEMAN · Post by **ONEEYEMAN** » Mon Oct 30, 2017 8:50 pm

Hi,
For the samples please check wxWidgets/samples/opengl folder.

Thank you.

almonj · Post by **almonj** » Wed Nov 01, 2017 6:31 pm

I could not get it to work on a panel, but I tried it with just a box sizer and it worked with added buttons. So I guess the panel wasn't really necessary?

ONEEYEMAN · Post by **ONEEYEMAN** » Wed Nov 01, 2017 6:53 pm

Hi,
Did you look at the samples?

Thank you.

almonj · Post by **almonj** » Thu Nov 02, 2017 12:42 pm

ONEEYEMAN wrote:Hi,
Did you look at the samples?

Thank you.

There are no samples that feature a glcanvas being used with a wxpanel.

Post by **doublemax** » Thu Nov 02, 2017 12:55 pm

If it doesn't work with a wxPanel, either the sizer structure or a parent-child relationship is wrong somewhere. But we'd need to see the code to say more.

almonj · Post by **almonj** » Wed Nov 15, 2017 7:49 pm

I have a frame class that only has a wxpanel and a sizer, the canvas class takes a wxpanel as parent.

This is what is looks like. If I change the canvas to take a wxFrame instead it works. What am I doing wrong?

I attached some files.

Thanks for any help, cheers

Frame_t.h

Code: Select all

#ifndef FRAME_T_H
#define FRAME_T_H

#include <wx/frame.h>
#include <wx/panel.h>
//#include <wx/glcanvas.h>

class Frame_t : public wxFrame
{
    public:
        Frame_t(const wxString& title);
        virtual ~Frame_t();

    protected:

    private:
       // wxPanel* m_panel;

        DECLARE_EVENT_TABLE();


};

#endif // FRAME_T_H

Frame_T.cc

Code: Select all

#include "Frame_t.h"

#include <wx/panel.h>
#include <wx/sizer.h>

#include <iostream>

#include "M_canvas.h"

Frame_t::Frame_t(const wxString& title)
       : wxFrame(NULL, wxID_ANY, title, wxPoint(742,300), wxSize(640, 480))
{

    wxPanel*  m_panel = new wxPanel(this, wxID_ANY);

    m_panel->SetBackgroundColour(wxColour(* wxGREEN));

    wxBoxSizer* sizer = new wxBoxSizer(wxVERTICAL);

    this->SetSizer(sizer);
    this->Layout();
    this->Centre(wxBOTH);




    wxGLAttributes attribs;
    attribs.PlatformDefaults().Defaults().EndList();
    bool accepted = wxGLCanvas::IsDisplaySupported(attribs);
    if (accepted)
    {
        std::cout << "normal display attribs are supported" << std::endl;
    }
    else
    {
        std::cout << "normal display attribs failed, trying other settings" << std::endl;
        attribs.Reset();
        attribs.PlatformDefaults().RGBA().DoubleBuffer().Depth(16).EndList();
        accepted = wxGLCanvas::IsDisplaySupported(attribs);
        if (!accepted)
        {
            std::cout << "display attribs cannot be set" << std::endl;
        }
    }


    if (accepted)
    {
        M_canvas* canvas = new M_canvas(m_panel, attribs);
        std::cout << "canvas created \n" << std::endl;
    }
    SetMinSize(wxSize(640,480));

    sizer->Add(m_panel, 1, wxEXPAND | wxALL, 10);
}

Frame_t::~Frame_t()
{
    //dtor
}


BEGIN_EVENT_TABLE(Frame_t, wxFrame)

END_EVENT_TABLE()

M_canvas.h

Code: Select all

#include "glew-2.1.0/include/GL/glew.h"

#ifndef M_CANVAS_H
#define M_CANVAS_H

#include "glew-2.1.0/include/GL/glew.h"

#include <wx/glcanvas.h>
#include <wx/dcclient.h>
#include <wx/panel.h>
#include <wx/sizer.h>

#include "GL_set.h"


class M_frame;


class M_canvas : public wxGLCanvas
{
public:
    M_canvas(wxPanel* parent, const wxGLAttributes& attribs);
    ~M_canvas();

    gl_init();

    void paint(wxPaintEvent& event);

private:

    wxGLContext* m_context;

    GL_set* gl;

    DECLARE_EVENT_TABLE();

};




#endif // M_CANVAS_H

M_canvas.cc

Code: Select all

#include "glew-2.1.0/include/GL/glew.h"

#include "M_canvas.h"

#include "Frame_t.h"


M_canvas::M_canvas(wxPanel* parent, const wxGLAttributes& attribs)
         : wxGLCanvas(parent, attribs, wxID_ANY, wxDefaultPosition, wxDefaultSize, 0, "canvas", wxNullPalette)
{

    //m_parent = parent;

    wxGLContextAttrs ctxAttribs;

    ctxAttribs.PlatformDefaults().CoreProfile().OGLVersion(3,3).EndList();

    m_context = new wxGLContext(this, NULL, &ctxAttribs);

    M_canvas::gl_init();

    gl = new GL_set();

};


M_canvas::~M_canvas()
{

    if(m_context)
    {
        SetCurrent(*m_context);
    }

    if(m_context)
    {
        delete m_context;
        m_context = NULL;
    }

}

M_canvas::gl_init()
{

    std::cout << "calling gl_init() " << std::endl;

    if (!m_context)
    {
        return false;
    }

    // Context needs to be set before openGL pointers are retrieved (glew)
    SetCurrent(*m_context);

    glewExperimental = GL_TRUE;
    GLenum err = glewInit();
    if (GLEW_OK != err)
    {
        // Problem: glewInit failed, something is seriously wrong.
        printf("Error: %s\n", glewGetErrorString(err));
        return false;
    }
    printf("Status: Using GLEW %s\n", glewGetString(GLEW_VERSION));

}

void M_canvas::paint(wxPaintEvent& WXUNUSED(event))
{

    wxPaintDC dc(this);

    SetCurrent(*m_context);

    gl->render();

    SwapBuffers();

    //Refresh(false);   // generates a paint event, false means do not erase background

}

BEGIN_EVENT_TABLE(M_canvas, wxGLCanvas)
    EVT_PAINT(M_canvas::paint)
END_EVENT_TABLE()

Post by **doublemax** » Wed Nov 15, 2017 8:54 pm

The problem is that the wxGLCanvas is not in a sizer, so there is nobody that tells it to fill the available space.

OTHT, putting the wxPanel in a sizer is not necessary as it will automatically fill the whole client area of the frame if it is the only child.

So in more or less pseudo-code it should look like this.

Code: Select all

wxPanel *panel = new wxPanel(this, ....);
wxGLCanvas *gl_canvas = new wxGLCanvas(panel...);
wxBoxSizer *sizer = new wxBoxSizer(wxVERTICAL);
sizer->Add(gl_canvas, 1, wxEXPAND ); // tell wxGLCanvas to grow in both directions
panel->SetSizer( sizer );

almonj · Post by **almonj** » Thu Nov 30, 2017 7:15 pm

doublemax wrote:The problem is that the wxGLCanvas is not in a sizer, so there is nobody that tells it to fill the available space.

OTHT, putting the wxPanel in a sizer is not necessary as it will automatically fill the whole client area of the frame if it is the only child.

So in more or less pseudo-code it should look like this.
Code: Select all
wxPanel *panel = new wxPanel(this, ....);
wxGLCanvas *gl_canvas = new wxGLCanvas(panel...);
wxBoxSizer *sizer = new wxBoxSizer(wxVERTICAL);
sizer->Add(gl_canvas, 1, wxEXPAND ); // tell wxGLCanvas to grow in both directions
panel->SetSizer( sizer );

This solved the problem, I got it to work. Thanks!

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